You can take up to two prevention courses a year and receive diamonds for each.
After you have completed your first prevention course, you are locked for 6 months.Why don't you look for other programmes under "Progress" during this period?
Under the tab "Rewards" you can see when you can start the next course.
Note: this function is not available to all companies. If it is not available to you, please reach out to your HUMANOO contact person